Image reading apparatus having a function for rectifying an image distortion caused by a curvature of a document surface and a method for executing the same

摘要

An image reading apparatus having a function for rectifying an image distortion caused by a curvature of a document surface, wherein the image distortion is rectified by duplicating image data that is a line of pixels in accordance with a varied amount of heights of a document surface, and a data conversion that is a image processing procedure in which the number of bits for pixels is reduced, is executed for the rectified image data. Data conversion elements whose number is the same as the maximum duplicated number "N", are arranged in a data conversion device, and the image data of a line to be duplicated arc input to the data conversion elements whose number is the same as duplicated number "n" of the line (n≦N), and then, n-line image data which is processed in n data conversion elements, are stored in a memory. Thereby, reducing a memory capacity needed for the distortion rectification can be achieved without lowering picture quality.